s=input()
c,cw=[None]*2;w=float("inf")
for i in range(len(s)):
    if s[i]=='c':
        c=i
    elif s[i]=='w':
        if cw!=None: w=min(w, i-cw+1)
        if c!=None: cw=c
print(-1 if w==float("inf") else w)